Corrosion-retarding compound and process of making the same



atented Apr. 34, 1931 i W A OR-RIN E. ANDRUS AND MILAN A. MATUSH, OF MILWAUKEE, WISCONSIN, ASSIGNORS TO A. 0. SMITH CORPORATION, OF MILWAUKEE, WISCONSIN, A CORPORATION OF NEW YORK COBROSION-RETABDING COMPOUND AND PROCESS OF G- THE SAME No Drawing.

This invention relates to improvements in corrosion retarding compounds and the process of makingirthe same and refers more particularly tothe manufacture of a compound to be used as an addition product to petroleum hydrocarbons or mineral oil-s, which are actively corrosive in their action to metals.

Hydrocarbon is employed as a base for the compound and is combined or has dispersed therein neutralizing material by oxidation of the hydrocarbon so that a relatively permanent suspension is produced.

The invention is primarily directed to correcting difliculties occasioned by the presence of corrosiveconstituents such as sulphur containing compounds and free hydrogen sulphide and free mineral acids contained in the petroleum hydrocarbons or formed therein by heat treatment.

The material is particularly adapted to correct or retard the corrosive action of petroleum oils when collected in storage or when heat treated in distillation or coking processes or in connection with the conversion of oils as in the cracking thereof.

Other objects and advantages of this addition product or corrosion retarding suspen- SlOil will be hereinafter explained in more detai Describing first the method of producing a typical batch of the material, a petroleum hydrocarbon having the characteristics of gas oil or the like is selected as a base. Any out or fraction above the normal boiling point range of kerosene has the characteristics adapted to this purpose and may be employed for the production of the material.

The less viscous oils such as gas oil have been.

found particularly adapted as they are more easily handled because less viscous and are more easily incorporated into the oil to be treated due to their greater fluidity.

To this gas oil base such as Midcontinent gas oil or California gas oil having Baum gravity of approximately 30 to. 32 isadded Application filed September 15, 1928. Serial No. 306,285.

an alkali such as caustic soda (NaOH) The mixture is heated while being agitated mechanically to a temperature of'from 300 to 400 F. During this heating operation there 15 supplied to the mixture an oxidizing agent such as air. The oxidizing material at these temperatures acts upon certain constituents of the hydrocarbon increasing the viscosity of the body and dispersing the caustic throughout the hydrocarbon in a discrete form anduniformly distributed. In addition it promotes the agitation and turbulence of the mechanical mixer. It is essential that the temperature be kept within a definite range in order to prevent excessive vaporization and oxidation of the material undergoing treatment. The batch after a period of from 4 to 6 hours results in a thickened liquid and in the case of some types of oils the mixture gelatinizes to a relatively stifi consistency. The viscosity in any event is materially increased over that of the original hydrocarbon stock used as a base. The caustic is found to be intimately dispersed throughout the oil in a relatively fine or discrete condition although the particles of caustic were introduced to the base stock in a relatively coarse state. The batch of material produced by passing an oxidizing agent through a hydrocarbon in the presence of a neutralizing material such as caustic soda is then added in a predetermined desired percentage to the oil to be'treated. This suspension is mixed and thoroughly ,incorporated into the corrosive oil to offset or counteract the active corrosive constituents. The addition of the material with the oil may be effected in innumerable ways it being essential only that the corrosion retarding compound is thoroughly dispersed throughout the mineral oil.

i As suggested the corrosion retarding compound may be used in connection with the storage of corrosive oils such as West Texas crude and other mineral oils having a high corrosive effect upon storage vessels and containers. In adding the corrosion retarding compound to oils undergoing distillation in steam or fire stills, coking stills or other types of distillation equipment a predetermined percentage of the material is pumped into the charging stock or may be added directly to the still. Similar methods for incorporating the corrosion retarding compound may be used in adding the oil to cracking stills or pipe stills where oil is to be treated under relatively high pressures and temperatures. The percentage of the corrosion retarding compound added in each case will vary according to the characteristic of the oil and the type of process in which it is to be used. Furthermore the percentages will vary when the oil is to be used for storage purposes relative to the percentages necessary for use in oils undergoing relatively high heat treatment. Actual tests indicate that from 1% to 5% of the neutralizing ingredient based on the weight of the oil treated is necessary for storage purposes depending upon the corrosive activity of the oil. In connection with oils which are to be heat treated a percentage range of from 2% to 5% may be used.

I-Iereinbefore caustic soda has been suggested as the only material adapted-to this particular purpose. The invention however, contemplates not only the use of such a neutralizing agent. but other materials as lime, (CaO), (Ca(OH) soda ash, (Na CO and combinations of these materials, and combinations of these materials with caustic soda (NaOH). lVhen the corrosion retarding suspension is to be used in connection with the conversion of hydro-carbons under pressure where relatively high temperatures are employed a predominance of lime in the suspension is found to give somewhat more satisfactory results, a suflicient caustic being used to effect proper combination of the neutralizing materials with the mineral oil as lime does not readily combine to form a satisfactory suspension when caustic is not present. In addition to these materials a satisfactory corrosion retarding compound has been produced by incorporating either iron oxide (F e 0 or sodium plumbitc (Na PbO into a mineral oil with or without additions of caustic soda to produce a s .t-istactory corrosion retarding compound. The method of incorporating these materials is substantially the same as that employed in producing a suspension of caustic soda alone. Best results in producing this addition product or suspension have been obtained when caustic soda is present during the oxidation of the hydrocarbon base. I

Besides using air as an oxidizing agent in producing the corrosion retarding suspension or compound the invention contemplates the use of ozone oxygen, peroxides and other suitable oxidizing agents.

The range of temperatures employed during the oxidation of a batch of the corrosion retarding compound is limited only within a range which will not produce objectionable or excessive oxidation and vaporization of the volatile constituents of the oil and which will give the proper or desire-d oxidizing ef fect. Normallyin producing a corrosion retarding compound with gas oil and caustic soda at substantially atmospheric pressure the temperature range will lie between 300F. and 400F. The suspension or corrosion retarding mix may be oxidized under pressure in which case greater or less temperatures may be required for ditlerent types of oils and the time necessary to produce a satisfactory suspension considerably lessened.

In the production of the material while it has been suggested that the hydrocarbon used as a base for'the corrosion retarding compound is heated, the heat may as well be supplied to the oxidizing material and with certain of the oxidizing agents very little heat is necessary to produce a satisfactory corrosion retarding suspension. Different types of oils may require somewhat diflerent temperature ranges during the preparation of the suspension.

No attempt will be made to explain the theory or character of the reaction which takes place during the making of the suspension as it has not as yet beenaccurately ascertained other than the actual physical characteristics witnessed in the practice of producing the material. Briefly it has been found that a neutralizing substance such as caustic soda or combinations of the materials mentioned can be dispersed through an oil body by heating the oil and treating it with an oxidizing agent whereby a compound or suspension is produced which has a decided corrosion retarding effect when added to a corrosive mineral oil in relatively small percentages.

This corrosion retarding compound seems to have a neutralizing effect upon free acids or corrosive sulphur containing compounds contained in the oil or produced in oils when sub ected to heat treatment. Also when thoroughly mixed with an oil the corrosion retarding compound has the ability to re main dispersed throughout the oil thereby belng uniform in its action throughout the Oll body and having no particular tendency to concentrate or accumulate and becoming local in its effect due to settling or otherwise.

This relatively permanent suspension would seem to depend upon the gelatiriizing or coagulation of certain of the hydrocarbon constituents which tends to collect about the discrete particles of the caustic as nuclei.

In addition to the corrosion retarding effeet of the compound or suspension hereinbefore described this suspension has also been satisfactorily used in the sweetening of certain hydrocarbon distillates by intimately combining the suspension with the distillate and after treatment removing the suspension either by settling out, centrifuging, filtration, or distillation.

With certain cut oils containinga considerable percentage of Water in emusified form noticeable in the case of caustic soda Varies with different types of oil.

Many tests have been made with the corrosion retarding suspension typical of which are the following, and from these a general idea of the characteristics of the material may be obtained.

A West Texas crude oil which was highly corrosive, producing a loss of 2.0 milligrams per square centimeter of copper in 215 hours under normal storage conditions was treated with the corrosion retarding suspension.

Employing caustic soda as a neutralizing agent the oil was treated with a corrosion retarding suspension containing 0.2 per cent of caustic soda. The loss in milligrams per square centimeter was decreased to 1.23. By increasing the percentage of caustic to 0.3

er cent the loss was decreased to .44 and by rther increasing the percentage of caustic to 0.4- per cent the loss was practically eliminated, amounting to .078 milligrams of copper per square centimeter, like periods of time elapsing in each test. Like efiects were obtained with soda ash and lime utilizing a small percentage of caustic soda to produce the desired suspension.

Below are tests which were made on Texas oils showing the corrosive eifect on copper and. iron at different temperatures and utilizing different percentages of the corrosion retarding material. Also results are tabulated on the corrosion efl'ect detected under cracking conditions. The results are actual tests which have been conducted to ascertain the advantages and corrosion retarding effect of the suspension when combined with oils under difi'erent circumstances, the oils "used being particularly difiicult due to their high corrosive action on metals.

Relative corrosion by West Texas oil in coking still:

Losamllligramper Maxl- Vapor Oil Type Proportion Analysis mum otoil oimlx. oimix dist.

temp.

l-a H 8. 3 FM Fl 94 i 8 E 6 .2

Crude- PlalnoiL- 850 F. 6.3 0.57307 1.43 Crude 600 cm oil; 7.7%caustlc 850 F. 3.04 0.35 4.370.097 100 cm mix. soda.

Crude" 550 cm oil; 7.7% caustic 850 F. 0.67 0. 0.55 0.024

150 cm'mix. soda.

Relative corrosion in cracking still conducted under pressure of 800# per square isiigh Iand temperatures of approximately Comparative tests of like character were conducted for the same time periods.

Although the process has been described as a batch operation in producing the suspension or addition product, the invention contemplates the making of the compound continuously.

The application of the compound to a corrosive oil will be governed by the requirements of the particular oil to overcome its corrosive action or tendencies.

The invention is hereby claimed as follows:

1. A corrosion retardin composition comprising a hydrocarbon aving a neutralizing agent intimatel incorporated therein and dispersed theret rough with oxidized products.

'2. A corrosion retarding composition comprising a partially oxidized hydrocarbon mixture of caustic soda and lime intimately incorporated therein to form a relatively permanent suspension.

6. A corrosion retarding composition comprising an oxidized h drocarbon having a mixture of caustic so a and soda ash intimately incorporated therein to form a relatively permanent suspension.

7 A corrosion retardin composition comprising mineral oil and iinely divided neutralizing material dispersed throughout the same and held in suspension therein by oxidation products of mineral oil.

8. A corrosion retardin composition comprising mineral oil and nely divided neutralizing material dispersed throughout the same and held in suspension therein by oxidation products of the mineral oil combined with a part of said neutralizing material.

9. A corrosion retardin composition comprising mineral oil and ely divided neutralizing material dispersed throughout the same and held in suspension therein by oxidation products of the mineral oil combined with caustic.

10. A corrosion retarding composition for treating mineral oils, comprising mineral oil and finely divided caustic dispersed throughout the same and held in suspension therein by oxidation products of the mineral oil.

11. A corrosion retarding composition for treating mineral oils, comprising mineral oil and finely divided caustic and lime dispersed throughout the same and held in suspension thlerein by oxidation products of the mineral o1 In witness whereof, we have hereunto signed our names.

MILAN A. MATUSH. ORRIN E. ANDRUS. 

